<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    div{
      width: 200px;
      height: 200px;
      background-color:red;
    }
    div:hover{
      width: 500px;
      height: 500px;
      transition: width 2s,height 2s;
    }

  </style>
</head>
<body>

<div></div>

</body>
</html>